The Symptom Questionnaire (SQ) is a yes/no questionnaire with brief and simple items. It contains state scales of depression, anxiety, anger-hostility, and somatic symptoms. It was developed from earlier versions to make the scales more sensitive for clinical research. The scales have been extensively validated. The psychometric properties of the SQ are somewhat different from those of similar scales. In double-blind, crossover studies, they tended to be more sensitive than other scales in discriminating between the effects of a psychotropic drug and placebo and were found to be highly sensitive in discriminating between distress levels of groups. In studies with small or moderately sized samples in which the sensitivity of scales is important or in populations that include subjects with poor verbal skills, the SQ seems to have advantages. The SQ is suitable for the measurement of distress and hostility in research and as a checklist in clinical work.